1. Field of the Invention
The present invention relates to an optical pickup incorporated into a CD (Compact Disc) player or a DVD (Digital Versatile Disc) player and, more specifically, to an optical pickup including a supporting structure for supporting a lens frame for holding an objective lens for irradiating a CD or DVD track with light, which is configured to be easily fabricated, require a reduced amount of component material and have high reliability.
2. Description of the Background Art
An objective lens for irradiating a recording medium such as a CD or DVD with light is secured to a lens frame and, by moving the lens frame along the surface of the recording medium together with the objective lens, information formed on the track of the recording medium can be read. In order to generate forces for moving the lens frame, plural coils such as a focus coil for adjusting the distance to the recording medium and driving coils for moving the lens frame along the surface of the recording medium are mounted to the lens frame.
In order to support the lens frame such that it can be moved by the forces generated from the coils, supporting wires having excellent elasticity are attached at their ends to the both side surfaces of the lens frame such that they sandwich the lens frame. The supporting wires are also attached at their root portions to a supporting-wire holding portion which houses a control circuit for adjusting the electric currents flowing through the coils mounted to the lens frame.
On the side surfaces of the lens frame to which one ends of the above-mentioned supporting wires are attached, the end portions of the lead wires constituting the above-mentioned coils are placed. Electric currents controlled by the above-mentioned control circuit are flowed through the above-mentioned supporting wires and thus the controlled electric currents are flowed from the end portions of the supporting wires for supporting the lens frame to the end portions of the above-mentioned coil lead wires. The focus coil adjusts the distance to the recording medium to draw focus thereto. The driving coils induce predetermined movements of the lens frame such as rotations thereof along the surface of the recording medium. Further, tilting coils for tilting the lens frame with respect to the recording medium are also placed and they are fed with electric currents through the supporting wires to cause predetermined tilting movements.
The structure for mounting the supporting wires to the lens frame and the structure for mounting the end portions of the above-mentioned various coil lead wires to the lens frame require procedures involving plural processes which affect the manufacture costs of the optical pickup. The above-mentioned structures for mounting the supporting wires and the end portions of the coil lead wires to the lens frame may induce reliability issues and therefore many propositions have been made. For example, there has been proposed a method which provides two parallel protrusions on one end surface of the lens frame, wherein the protrusion nearer the supporting-wire holding portion is provided with through-holes for passing the supporting wires therethrough, the end portions of the coil lead wires are wound around the other protrusion, and the supporting wires are secured to the wound portions with solder.
Further, the provision of two protrusions on a single side surface as above requires plural processes and also increases the weight and the material cost. Therefore, there has been proposed a structure in which a single protrusion is provided on one side surface of the lens frame, the single protrusion is provided with a winding terminating portion for winding the end portions of the coil lead wires therearound and through-holes for the above-mentioned supporting wires near the winding terminating portion, and the supporting wires passing through the through-holes and the wound lead wires are connected with solder (see Japanese Laid-Open Patent Publication No. 2002-269781).
In the above-mentioned structure in which a single protrusion is provided on one side surface at a single height, the portion around which the end portions of the coil lead wires are wound and the supporting wires passing through the through-holes are separated from each other when viewed from above, thereby requiring a large amount of solder in solder-connecting them. Further, the lead wires are tend to be wound many times in order to reduce the distance between the supporting wires and the lead wires when solder-connecting the supporting wires and the lead-wire wound portion. This may result in an increase of the weight and loss of balance during the movement of the lens frame.
Further, when attaching the supporting wires to the lens frame during an actual procedure, the lens frame is not supported until the lead-wire wound portion and the supporting wires are solder-connected, which makes the procedure complicated and difficult. Further, even if a winding slot is provided at the portion around which the lead wires are to be wound, it is difficult to wind the lead wires and, particularly, when it is desirable to manually wind the coil end portions, it is not easy to wind them manually. Further, when two protrusions are provided on one side surface and the lead wires are wound around one of the protrusion as described above, the other protrusion is contacted with the lead wires and becomes obstruction during the winding of the lead wires, thereby inducing the problem of complicating the procedure.